In this podcast, Scott Davert walks us through the process of updating to a newer version of iOS using iTunes on a Windows PC. In this demonstration, he is using Jaws on a computer running Windows 7.
I updated to ios 9.0 through ITunes on Windows 7 PC and it went well. However, as I am updating to 9.0.1, iTunes is downloading the entire ios package of 1.47 GB. How to make iTunes download only the required update which should not be very large in size?
I'm not sure, I noticed it took longer to upgrade via iTunes from 9 to 9.0.2 as well, maybe when you download it on the PC, that's just how it behaves? If so, that's quite annoying.
OTA/ Over the Air
For some people who are confuse OTA and Over the Air means the same thing.
The OTA updates provides a delta update only while iTunes provided the whole build.
Delta include small size while whole build unpack the big file using PC or Mac
Answer to tripolice there not way to download only the Delta package using iTunes.
updating via iTunes the file size to each iOS device is completely different
and I would understand that for newer iOS devices is to much larger
to update iPhone 6 not matter from: iOS9/ 9.01 or 9.02 the entire iOS package is 1.8Gb
ADVICE from apple Tech support
If there is a problem after installing the delta update OTA, restoring the iPhone with iTunes to install the whole build for the update may resolve the problem.
The most common problems are: Battery life, Wi/Fi Problem, BlueTooth Issue, or Software Bug.
Using iTunes The full update is likely to be more stable
There the possibility of minus glitches
iTunes always downloads the full OS and installs it. OTA only downloads the changes since the last update.
The difference is which files are replaced--with the iTunes update, it replaces all of the OS files even if some of them are the same copies that were present prior to the update.
The full update is likely to be more stable, as you could have a modified version of a file that the OTA updaters didn't expect to be modified, causing an incompatibility. The full installer will replace all files, and likely replace the unexpectedly modified file, restoring compatibility.
Using iTunes you are able to know the situation in which the update process
extracting, installing, verifying software with apple, iPhone rebooting and all those details that updating over the Air or OTA couldn't announce
While keeps silence through this process only show the apple logo on the screen and some progress indicater but impossible to read for voiceOver it takes about 10 minutes or less until final reboot.
to Scott as always grate podcast only a small NOTE to your audio advice to be more complete for some users
There the possibility to know the estimated time remaining when iTunes is downloading the file doing Tab or Shift tab will find a button control where show the download progress and estimated time very similar as LCD section for Mac XX.